Methane is a critical component of Earth's carbon cycle that contributes 18% to the Earth's warming. It is the major constituent of natural gas and biogas, composing up to 80% of the latter. CH4 is emitted from a variety of natural and anthropogenic sources. Human-related activities, such as fossil fuel production (e.g., underground coal mining, oil and gas production), agriculture (e.g., enteric fermentation in livestock, manure management, and rice cultivation), landfills, and municipal wastewater are major contributors of global CH4 emission. Anthropogenic CH4 emission accounts for more than 60% of the total CH4 budget (≈300 tg yr−1).
CH4 is not only one of the major contributors for climate change, it is also the primary target for near-term climate regulation. Stranded natural gas (SNG), oil-associated gas and almost all waste-derived biogas are not economically feasible sources of energy due to small size or remote location. Each year, up to 116 million tonnes of oil-associated methane and 40 million tonnes of biogas (equivalent to 30% of the total US transportation fuel) are flared, which represents lost energy (five quadrillion BTU of fossil fuel energy), unnecessary greenhouse gas emissions and dangerous air pollution. Strategies for effectively converting CH4 into valuable compounds offer promising new technologies for global warming stabilization and possibly reduction. Methane-rich biogas offers a renewable alternative to fossil natural gas as a feedstock and intermediate in bioprocesses, adding to our capacity for biofuels and biobased products to supplement those available from lignocellulosics or algae.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.